The aims of this research are to: (a) estimate the prevalence, incidence, and other epidemiologic characteristics of depression in adolescents aged 15-18; (b) develop an efficacious screening test for the detection of depression in adolescents; and (c) identify the pattern of psychosocial risk factors associated with depression in adolescents. To accomplish these goals, screening tests, a battery of psychosocial exposure variables, and diagnostic interviews will be administered to 1,500 adolescents and their parents randomly selected from eight public high schools from rural and urban areas in Oregon during each of the first 3 years of the project. The screening tests, the psychosocial risk factor battery, and the diagnostic interviews will be readministered to these 1,500 youngsters and their parent(s) after an interval of 1 year. The screening tests will include the Center for Epidemiological Studies Depression Scale (CES-D), the Beck Depression Inventory (BDI), and items dealing with anxiety, suicidal ideation, conduct disorder, and hypomanic behavior. The Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) and the Longitudinal Interval Follow-up Evaluation (LIFE) will be used to make diagnoses and to study the longitudinal course of depression. The exposure variables will include a wide range of measures designed to assess cognitive functioning, social-interactional behavior, engagement in pleasant activities, occurrence of stressful life events, and familial characteristics. Data will be collected from several sources (self-report, psychological tests, diagnostic and other ratings, and behavioral observations) and the approach can be characterized as multimethod, multitrait, and multivantaged. By generating data about the magnitude of the problem of depression in adolescence, the results of this study will assist mental health planners responsible for providing adequate treatment facilities for depressed adolescents. The availability of a cost-effective screening test as the first of a two-stage case-finding procedure will facilitate the efforts of other investigators conducting scientific studies of depression in adolescents. Knowledge about an extensive array of psychosocial risk factors associated with depression in adolescents will have implications for the design of preventive and treatment interventions and for depression theory.